Most devices to date use the frequency response of either pulses or a swept frequency technique to determine range. Many systems have performed Fourier transforms in one way or another to extract the frequency information with the limitation that at least one full cycle of information is needed to determine a particular frequency response. The following formulas have been used to describe the optimum resolution of pulse and swept frequency systems to date.
R=C.tau./2 for pulse systems PA1 R=range resolution in meters, PA1 c=3.times.10.sub.8 =speed of light, PA1 .tau.=width of the transmitted pulse and PA1 R=150/BW(MHz) PA1 R=range resolution in meters PA1 BW=system bandwidth in MHz
where
where
In other words, the higher the bandwidth of a system, the greater the optimum resolution. That results in systems of high resolution that require high bandwidths which become increasingly difficult to implement with higher resolutions.